Move <main> and .sidebar markup out of PHP

Add more efficient LESS with variables

Add new line to _variables.less

Add sidebar class to body element instead of main element

Change body sidebar class to .sidebar-active

Change body sidebar class to .sidebar-primary

Correct spacing issues
Add dev dependency status badge
Merge pull request #1090 from CFXd/move-main-and-sidebar-markup-out-of-php

Move <main> and .sidebar markup out of PHP and into LESS
Close #1127 - Assume prod if WP_ENV is undefined
Remove mention of feature removed from Soil
Update devDependencies
Roots 7.0.1